Where have our red-legged partridges gone?

http://www.rspb.org.uk/Images/redleggedpartridge_tcm9-18426.jpg?width=530&crop=(282,326,936,694)

Until about a week ago, for at least a year, there was a pair of red-legged partridges always to be seen in our Close and in the garden. Then a third bird appeared - maybe a rival male?  Since then, all have disappeared. It is a total mystery. Birds have bird minds and bird brains, but I for one miss their presence.

See http://www.rspb.org.uk/wildlife/birdguide/name/r/redleggedpartridge/ .